BAQOUBA, Iraq - U.S. armored vehicles stand idle on the edge of western Baqouba's apartment blocks. The soldiers who normally ride in them have left on foot patrols - a simple, but apparently effective tactic being used against insurgents planting increasingly large and devastating bombs deep underground.
Bringing troops onto the streets in bloody places such as Baqouba carries some new risks, including small-arms fire and rocket-propelled grenades that armored vehicles can usually repel. But it's designed to avoid a more serious threat: the buried explosives that can take out Humvees and the bigger Strykers that can hold 10 soldiers.
The weight of a single soldier is insufficient to trigger such bombs, which might be planted 10 feet underground and packed in unusual casings such as refrigerators. Insurgents are hesitant to "waste" a large bomb by triggering it using a remote control to kill a single soldier, said U.S. officers involved in an offensive in the capital of Diyala province northeast of Baghdad.
The foot patrols have been credited with preventing heavy U.S. casualties in the battle for Baqouba. U.S. deaths from the bombs - which the military calls improvised explosive devices, or IEDs - dropped in Diyala from at least 16 in May before the 10,000-troop offensive to just two so far this month, according to an Associated Press count based on Defense Department reports.
But that sharp drop is not being reflected in other parts of Iraq. In May, at least 68 U.S. soldiers were killed by road bombs, or 67 percent of all military deaths that month, according to the AP analysis. This month, at least 51 deaths were linked to IED blasts, or60 percent of the total.
And avoiding the bombs does not make them go away.
One of Baqouba's main thoroughfares is so packed with IEDs that the U.S. military is considering declaring it "irrevocably mined," said Col. Steve Townsend, commander of the Army's 3rd Brigade, 2nd Infantry Division.
U.S. forces would then build their own road - alongside the mined one - and guard it 24 hours a day, said Townsend, 47, from Griffin, Ga.
"We have yet to clear the roads well enough to penetrate with our vehicles," he said. "We're infantry, and we're comfortable on foot, anyway."
Once U.S. troops leave Baqouba, the task of keeping these roads clear of IEDs would fall to Iraqi security forces. But American commanders estimate it will be months - or longer - before Iraqi forces can do the job on their own.
Main roads throughout this city are dotted with huge craters, some 10 feet wide and just as deep. Military vehicles swerve gingerly around them. Gunners train their weapons on the holes, watchful for secondary devices covered by garbage.
Before the Americans shifted their tactics, the bombs took a heavy toll.
On May 6, a deep-buried IED killed six U.S. soldiers from Townsend's brigade serving in Baqouba, along with a Russian photographer embedded with them. The blast flipped their Stryker vehicle - an eight-wheeled, 37,000-pound troop carrier - upside down and tore out the interior, killing everyone inside except the driver.
Most of the bombs apparently were laid months ago, but about 30 IEDs were planted along Baqouba's main thoroughfare before the start of the current U.S. operation last week, said Maj. Robbie Parke, spokesman for the 3rd Brigade, 2nd Infantry Division, which is doing most of the fighting in western Baqouba.
It's a sign that insurgents likely knew the offensive was coming.
"They were putting in berms, and had backhoes digging trenches ahead of time. We have UAV [unmanned aerial vehicle] footage of all of this," said Parke, 36, from Rapid City, S.D.
In the following seven days, U.S. troops discovered and safely detonated 50 more IEDs - more than half of them deeply buried - in western Baqouba alone, Townsend said.
Some were discovered by unmanned drones equipped with temperature sensors that can scan for cold spots under the otherwise blazing hot asphalt in summer, another U.S. officer said.
Deep buried IEDs usually consist of hundreds of pounds of homemade explosives, though sometimes they employ military-grade weapons such as mortar rounds, said Maj. Doug Baker, the executive officer for the 5th Battalion, 20th Infantry Regiment, under Townsend's command. They are buried at least 3 feet deep, though some have been found 10 feet down, he said.
Insurgents lie in wait to detonate the explosives manually. "They'll let you drive over it nine, ten times, and on the 11th time, they pull the cord," said Baker, 38, from Goose Creek, S.C.
Traditionally found in rural areas, where dirt roads and canals provide soft terrain for planting explosives, deep-buried IEDs are increasingly being discovered on paved roads in urban areas, U.S. officials said.
"In some cases, they're tunneling from the side [of the road], and in other cases they pour gasoline on the road and set it on fire, softening the asphalt so they can dig through it," Baker said. "Then they do the same thing to essentially repave the area afterward."